The present invention relates in general to motor vehicle suspension systems which include controllable ride height, for example by an air suspension control system, and, more particularly, to load leveling control for such vehicles which operates in response to opening a passenger or cargo compartment.
Motor vehicle suspension systems are connected between the body of the vehicle and the wheels to determine the ride and handling of the vehicle. Conventional suspension systems include springs and shock absorbers which are typically fixed such that the ride and handling are fixed and the level of the vehicle depends upon the loading of the vehicle.
More advanced suspension systems include controllable elements such as variable damping shock absorbers which permit two or more damping factors to be selected as needed. Controllable springs may also be included. Such springs are typically pneumatically or air controlled and are inflated to increase the spring rate of the overall vehicle spring system and deflated to decrease the spring rate. Vehicle suspensions including controllable springs may be electronically controlled to maintain a predetermined vehicle ride height relative to the wheels, regardless of fluctuations in the passenger and/or cargo weight. By maintaining ride height, heavily loaded vehicles and vehicles having uneven weight distributions benefit from improved outward appearances, ride and handling.
Unfortunately, existing vehicle suspension systems stop standard leveling action the moment a door of the vehicle is opened. While some systems stop all leveling action if a door is open, others could raise the vehicle with an open door to prevent damage to under body and trim components including doors, running boards and the like from contact with curbs and other obstructions as the vehicle is loaded. However, if a vehicle is being unloaded, it may be raised above the height at which its trunk lid or hatch door extends creating the possibility of damage to the trunk lid or hatch door due to contact with obstructions above the vehicle. Damage to the trunk lid or hatch door may occur whether a vehicle door is open or not since cargo compartments are not monitored in existing systems.
It is, thus, apparent that there is a need for an improved suspension control system to reduce the possibility of damage to a vehicle trunk lid or hatch door while passenger or cargo compartments are open.